The present invention relates to a printer, and more particularly to a printer which can serially print a function digit and numeral digits.
Recently, small-sized desk calculators or measuring instruments have been additionally provided with a small-sized and light-weight printer, and it has become possible to immediately print a displayed result on recording paper. Regarding contents to be printed on the recording paper, not only the counted numerical result but also a function digit can be usually printed. The prior-art printer which can print the numeral digits and the function digit in this manner typically comprise a type wheel which has type elements corresponding to various function symbols disposed on its periphery, as well as a type wheel which has type elements corresponding to numerals disposed on its periphery, and two print hammers which correspond to the respective type wheels. In operation, a function digit is printed with the first hammer, whereupon the printing operation for the function digit is ceased. Subsequently, the second print hammer is actuated and is successively shifted from the least significant digit of the numeral digits so as to print the predetermined numerical value.
In this manner, the prior-art printer is equipped with two hammers for printing the function digit and for printing the numerical value, respectively, and operates only one of them at a time through the control of a change-over mechanism. It is therefore disadvantageous in that a driver mechanism for the hammers becomes considerably complicated and that the assemblage is cumbersome. Other disadvantages are frequent operating troubles and very high cost.